1. Field of the Invention
The present invention relates to organic light-emitting displays. In particular, the present invention relates to an organic light-emitting display having a photo sensor capable of providing improved luminance control thereof.
2. Description of the Related Art
In general, an organic light-emitting display is a flat display device where voltage may be applied to a plurality of layers interposed between two electrodes, i.e., an anode and a cathode, to combine electrons and holes to form images. More particularly, the conventional organic light-emitting display may include a hole injection layer, a hole transport layer, at least one organic light-emitting layer, an electron injection layer, and an electron transport layer. Accordingly, holes may be injected into the hole injection layer from the anode electrode and transported into the organic light-emitting layer through the hole transport layer. Similarly, electrons from the cathode may be injected into the electron injection layer and transported to the organic light-emitting layer through the electron transport layer. The transported holes and electrons may be combined with one another in the organic light-emitting layer to form excitons, and thereby, emit visible light.
The conventional organic light emitting layer of the organic light-emitting display may deteriorate over time and, thereby, reduce display luminance. In other words, once the organic light-emitting layer deteriorates, the brightness of light emitted from the organic light emitting layer may deviate from the required brightness value, thereby reducing the image quality of the organic light emitting display and its overall lifespan. Attempts have been made to improve the brightness of the organic light-emitting display device by incorporating a photo diode therein, such that a constant electric signal from the photo diode may trigger constant luminance from the organic light-emitting display, regardless of the deterioration state of the organic light-emitting layer. However, the conventional photo diode may have a limited electric signal output, thereby limiting the luminance control efficiency, i.e., reducing the luminance adjustment range.
Accordingly, there exists a need for an organic light-emitting display device with a photo diode capable of controlling luminance thereof by efficient electric signals.